Parsley soda was an "in" drink at the time of the In Auction in The Ersatz Elevator. Esmé Squalor, the fashionable sixth most important financial advisor of the City, drank parsley soda during this time. Parsley soda replaced aqueous martinis as the "in" drink, although parsley soda is portrayed as having an unpleasant and disgusting taste. Even Count Olaf spits out the drink after making a toast to Esmé in her penthouse.
Parsley soda also appears in the movie, shown in the fridge at the Last Chance General Store. In the Grim Grotto, the Baudelaires are offered Parsely soda by Phil (nicknamed Cookie by Captain Widdershins.) They say they do not like the drink.